Alloy



Patented July 27, 1937 ALLOY Horace F. Silliman, Waterbury, Coma, asignor to The American Brass Company, Waterbury, Conn, a corporation of Connecticut No Drawing. Application March 14, 1935 Serial No.. 11,066 1 12 Claims. (01. 148-212)- My invention relates to alloys of copper, beryllium; and iron which can be hardened and ened by a precipitation hardening heat treatment.

This heat treatment consists of first quenching the alloys from a high temperature, within the range approximately 600 C. to 850 C. and then reheating for a definite length of time within the range approximately 200 C. to 400 C. The time required for this heat treatment depends upon the temperature employed, being shorter at the higher points of temperature. For example, at a temperature of about 275 C. the time required would be from one to three hours depending upon the properties desired.

The alloys may or may not be cold'worked by rolling, drawing, hammering, etc. before or after either or both parts of the aforesaid heat treatment. There are structural changes in the alloys.

in both temperature ranges which bring about the hardening and strengthening.

One difliculty encountered in manufacturing copper-beryllium alloys containing 1 percent to 4 percent beryllium has been that the high temperature required for the first part of themecipitation hardening treatment produces grains of a very large size. This grain size persists after the precipitation hardening treatment with the result that the finished product is coarse grained and low in percentage strength as determined by the tension test.

I have found that the addition to the copper alloy containing l'percent to 4 percent beryllium, remainder copper, of 0.10% to 3% iron will greatly reduce the grain size produced by the high temperature anneals. The preferred range, however, is approximately 2.0% to 2.25% beryllium, 0.2% to 0.5% iron, and balance copper.

The coarse grain size of the beryllium-copper alloys without the iron addition is detrimental to products made from it in several ways: first, the coarse grain size gives a rough, "orange peel surface to articles made. by deep drawing sheet metal so that fine'finishing is difiicult except at greatly increased expense; second, the percentage elongation of the coarse grained alloys is extremely that the addition of from .10 per cent to 3 percent iron minimizes the disadvantages resulting from the coarse grained structure of the binary beryllium-copper alloys containing 1 percent to 4 percent beryllium.

Another distinct advantage gained by adding iron to the beryllium-copper alloys is the elevation of the recrystallization temperature. It is a well known fact that all copper alloys which have been hardened by cold working begin to soften at a certain minimum temperature when heat is applied. The structural change which takes place as the alloy softens is usually referred to as recrystallization. Unfortunately cold worked binary beryllium copper alloys undergo recrystallization in the range of temperatures most suitable for the precipitation hardening treatment and it is therefore impossible to utilize to the fullest extent hardness resulting from both cold working and precipitation heat treatments.

' At temperatures where the precipitation hardening heat treatment is most effective the recrystallization sets in and the hardness resulting from cold work is lost. a

The addition of iron to the beryllium copper alloys raises the recrystallization temperature enough so that the effect of cold work is not destroyed at the precipitation Hardening temperature and therefore a much harder material can be obtained. 30

A further benefit derived from the iron addition is the widening of thetemperature range through which the copper-beryllium alloys may be hardened and strengthened successfully by the final low temperature heat treatment.- The pres- 35 ence of iron in the solid solution makes the alloy more stable and less sensitive to the small variations in temperature which are encountered in commercial heat treating furnaces. This makes it possible to obtain uniform hardness all over large pieces of my alloy and also to obtain uniformproperties in successive lots of articles. Thus although the binary copper-beryllium alloy can by careful handling be hardened by heat treatment in the range of 200 C. to 400 C. as stated above, for practical purposes this is confined to the range of about 250 C. to 300 C., while with the addition of iron as described it is practical to heat treat in the whole range from 200 C. to 400 C. V

In these ways the addition of iron to the copper-beryllium alloys is distinctly beneficial and makes the alloys more practical and more useful than similar alloys without the iron addition.

I am aware of French Patent No. 721,767 55 granted to Siemens Halske A ktiengesellschait and published March 8th, 1932, but that patent.

is essentially based on the presence of material amounts of manganese. No specific advantages are disclosed as being secured by addition of numerous other elements among which is mentioned iron. In my alloy the presence of manganese is not required.

My new alloy may be made into a variety of wrought forms, sheet, strip, rods, tubes, wire, special shapes by' hot and cold rolling, drawing, extruding, pressing, forging, hammering, swaging, etc. or it may be used in the form of castings without any mechanical treatment. Applications for these alloys lie in fields requiring high strength, high elastic limits, high hardness and high endurance limit combined with high corrosion resistance, fair electrical conductivity, non-magnetic properties and non-sparking properties such as springs, contacts, wear resisting parts for clocks, watches and instruments, nonsparking tools, knives, nuts and bolts, dies, diaphragms, valve parts, fuse clips, welding electrodes, parts for electrical devices, etc.

Having thus set forth the nature of my. invention, what I claim is:

1. An alloy containing approximately 1% to 4% beryllium, 0.10% to 3% iron, balance copper whereby the grain size is reduced and the recrystallization temperature raised over a similar beryllium-copper alloy without iron. 7

2. An alloy containing approximately 2.00% to 2.25% beryllium, 0.20% to 0.5% iron, balance copper.

3. A heat hardened and strengthened alloy containing approximately 1% to 4% beryllium, 0.10% to 3% iron, balance copper.

4. A- heathardened and strengthened alloy containing approximately'2.0% to 2.25% beryllium, 0.2% to 0.5% iron, balance copper.

5. A precipitation hardening alloy containing approximately 1% to 4% beryllium, 0.10% to 3% iron, balancecopper.

6. A precipitation hardening alloy containing approximately 2.00% to 2.25% beryllium, 0.2% to 0.5% iron, balance copper.

'7. An alloy of approximately 1% to 4% beryllium, 0.10% to 3% iron and balance copper which has been hardened and strengthened by quenching from a temperature range of from 600 C. to 850 C. and then reheated within the temperature range of 200 .C. to 400 C. for a suflicient temperature range of 200 C. to 400 C. for a sufiicient time to increase its hardness and strength.

9. In the heat treatment of copper base alloys containing from approximately 1% to 4% beryllium, 0.1% to 3% iron and balance copper, the process which comprises heating such an alloy to a temperature in the range of 600 C. to 850 C., quenching and reheating to a temperature in the range of 200 C. to 400 C. for suflicient time to increase its strength and hardness.

10. In the heat treatment of copper base alloys containing from approximately 2% to 2.25% beryllium, 0.2% to 0.5% iron and balance copper, the process which comprises heating such 3 an alloy to a temperature in the range of 600 C. to 850 C., quenching and reheating to a temperature in the range of 200 C. to 400 C. for suificient time to increase its strength and hardness.

11. An improved article comprising a heat hardened copper base alloycontaining from approximately 1% to 4% beryllium, 0.10% to 3% iron, and balance copper, said article having increased hardness and strength obtained by heating said alloy to a temperature within the range of 600 C. to 850 C., quenching and age-hardening at temperatures in the range of 200 C. to 400 C.

12. An improved article comprising a heat hardened copper base allloy containing from approximately 2% to 2.25% beryllium, 0.2% to 0.5% iron and balance copper, said article having increased hardness and strength obtained by heating said alloy to a temperature within the range 0! 600 C. to 850 C., quenching and agehardening at temperatures in the range of 200 C. to 400 C.

HORACE F. SILLIMAN. 

